Yellowstone Bears Actually Eat Moths for Food

It turns out that bears can eat 40,000 moths a day

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Bears are well known to be voracious eaters, stuffing their faces with everything from salmon to campers snacks all spring and summer in preparation for the winter. But they also have one source of food you probably never would have thought of—moths. It turns out that bears can eat 40,000 moths a day.

One group of scientists analyzed bear scat and revealed that a foraging grizzly could gobble 40,000 moths in a day. At that rate, the bear can consume about one-third of its yearly energy requirements in just 30 days. However, the moths’ habits—including where they mated, when they mated and how far they could migrate—have remained a mystery until recently.

It turns out that moths are both delicious and full of fat. One study found that moths can get up to 83 precent fat and are more energy dense than ground squirrels, trout or pine nuts.

Not all bears can rely on these tasty moths though. Yellowstone grizzlies happen to live in the midst of the miller moth migration path, and have learned to munch on the moths. Should the moths decline, scientists are a worried that the bears might lose an important food source. And since miller moths are pests for most farmers, there’s a good reason to worry that they might be wiped out.

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About Rose Eveleth

Rose Eveleth is a writer for Smart News and a producer/designer/ science writer/ animator based in Brooklyn. Her work has appeared in the New York Times, Scientific American, Story Collider, TED-Ed and OnEarth.

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